Projection apparatus.



N. W. DEXTER & W. B. MATHER.

PROJECTION APPARATUS.

'APPLIGATION FILED 11.111. 21, 1911.

1,009,897, Patented N0v.28, 1911.

NATHANIEBW. DEX'IER WARREN B. HEATHER, 01*? L03 .ALNGELES, UZ-iLIFORNIA,

.ASSIG-NOIRS T0 UNITED STATES ELECTROGRAIPHIC COMPANY,

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A CORPORATION 01!" PROJECTION APPARATUS.

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Specification of Letters Patent.

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Application filed. March 27, 1911. Serial No. emote.

It's all whom it may concern:

Be it known. that we, NA'ITIANIEL Vi Dnx'run and Vl ARREN B. Mirrnnn,bot-h citiszans or the United States, residing at Les Jingeles, in thecounty of Los Angeles and State cit" Calitornia, have invented new anduseful ln'iproveinents in Projection Appw ratus, of which tion.

{this invention relates to improvements in apparatus for the projectionof pictures, Writings, etc; and the invention consists particularly inthe provision. of means whereby Writings, drawings, etc, can be enlargedand projected upon a screen so that they can he view by large audienceduring the process of making.

The distinguishing feature of our invention is the provision of a glass,or other Hll'Bllli plate, placed in the beam or projected and in such aposition with tion to the apparatus that it can be easily Written ordrawn upon with the aid of a suitable pencil or other means. At presenta jiiencil known as a grease pencil is used, this being the onlysuccessful article for marking on glass of which We are aware; hut othermedicare not thus excluded from the scope of our invention. The glassplate is placed on an adjustable holder, the glass being easilyaccessible to the operator from shove. The plate is placed directly infront of the usual slide holding; member, none of the ordinary featuresor the projection lantern being thereby changed in the leastparticular.[is the slide holder and glass panel are at different places withrespect to the focus of the light passing through the condenser, it isnecessary to change the position or the objective for the clear projection of the representations on the slide and on the glass panel.Stops are provided so that the objective may be moved quickly andaccurately to each tocul position, so that a change from the projectionof matter on a slide to matter on the glass platecan he cft'ectedquickly. However, the distance between the ordinary slide and the glassplate is small. and it is possible, With a small amount ofindistinctness, to simultaneously project matter on both slide andplate. In this Way novel cficcts are olotained.

the following is a spec fics l fiiace by a thumb s 13 is mounted oncapable of use on any of the various it.

in the ac oinpanying (h-airings: Figure 1 is an elevation showing thegeneral arrangement of a projection lantern equip 'iod with L ourimproveiucnt, and showing the path. oi. a set of rays thrr theapparatus. Fig. 2 is an enlarged longitudiual, ion showing theconstruction of our invention and of the parts of the projection lanternimmediately adjacent thereto. Fig. 3 is a cross sec tion taken on line8-3 of i r 2.

In the drawings 5 designates a hasc hoard on which the apparatus ismounted, hon 6, which holds the light 7, being; mounted directly on base5. Condenser 8 secured to box 6 by means of a si'nall bracket 8 andthumb nut 10, the Whole forward portion of the apparatus being thusrcn'iovahle lir box 6. t londenser 8 contains the usial set ofcondensing lenses 9, which are shown in the present case asplano-convex. The path of rays from light Y through this condciiser isgenerally indicated in Fig. l, the rays in'ipinginrg on the lensesbeing; tl'irown through the forward portion of the apparatusandcondensed toward objec ive l1. tlbjective ll. retracts these rays inthe ordinary manner to form a real image at some pointat the right inFig. 1, the rays crossing at a point some distance in front of objectivell so that the image formed is reversed frcnii the re"): itation put inthe path of the rays between the comflenser and the objective. Theohjimtive is nioiiuitcifl on r rod 12 titted into socket lfil amt-heldin err i c that the obted vertically. hloclret liding hoard fie-l whichmay be inove til he i' if and it. Both of these stone are adjustable inposition and are set points so tl the ohjcct'ive is in proper positionto throw a clear image f the matter either on r l s or on the glassplate on. a screen to :3; ht, and

jective may he adji'.

or l

above descrihed apparatus is more typical of the arrangement new in use.Uur invention is not restricted hination With this specific form, it

of projection apparatus new in Immediately in iront of cor.

located slide receptacle 20. This recptacleedge rest in notches 26 ofrack bars 23 and,

to rest against a bar 27 placed across the upper end of: the boxin-notches24. By means of this arrangement the position of the glasspanel holder may be changed to suit anyv requirements. For average usewe place the holder in about the position shown so that the end ofpencil 28 caneasily reach glass plate 29 held in the holder. The glassplate simply rests against the holder in a clip 30 at the loweredge ofopening 31 in the holder.

The operator holds the pencil in some position such as. that shown andwrites on the glass plate in a natural manner as it appears to himlooking down upon the plate while writing or drawing. The angularposition of the plate renders the work easy",

it being possible to draw or write anything on the glass plate that canbe done on a surface resting horizontally" before the worker. As shownin Fig. 3, writing which appears normally to the operator looking downupon the rear surface of the glass, appears reversed in both directions.when viewed from the front. As the projection reverses the showing inboth direct-ions, the writing is thrown upon the screenin a normalposition as viewed from the side on which the projection apparatus islocated. Aper tures 42 are provided in the sides of box 22 so that-along glass panel may be used and moved horizontallyinto the field oflight. On such a long plate, indicated in dotted lines in Fig. 3,writing or drawing may be continued from one end to the other by merelysliding the platealong as the work progresses. This method has certainadvantages. For instance, along panorama maybe made and shown with ease.

In addition to the glass plate we sometimes place a transparent box 40in the path of the rays directly between the condenser and the glassplate. This box is designed to hold a liquid a1, such as water, and tothereby prevent any intense heat from reaching the glass plate and thehand of the operator. This box may be filled with a coloredliquid or itmay be filled with various colored liquids. One of the main uses whichwe put this box to is a novel representation of interniingling colorswhich seem to fioat around and into each other. By placing a heavyliquid with-in a lighter liquid of another color, the heavy liquid willsin-k in the box and therefore appear to rise in the projection on thescreen. As the movement of these liquids is caused by gravity, exactsimulations of clouds of smoke moving in the atmosphere can be made. Byinjecting a quantity -of appro priately colored fluid behind astationary representation of a volcano, the volcano being pictured onthe slide, a realistic representation of an eruption may be made.

Such representations as these may be carri'ed on in combination withsketches and I writings made on the glass plate, both representationsbeing simultaneously projected into the same field of view. 7

Our invention consists primarily in the provision of means forprojecting writings and drawings and other representations while beingmade, placed directly in the beam of light projected from the projectionapparatus. The apparatus is applicable to any form of representation, asis illustrated by the use of the two distinct forms of representationbefore described. With this in view the following claims are intended tobroadly cover any device capable of being used for the projection offormative representations.

Having described our invention, we I source of light, a supportingmember, a

transparent plate mounted on the supporting member in the path ofapproximately horizontal rays from the source of light, the plate beinginclined upwardly and away from the source of light so as to render itssurface toward the source of light accessible from above.

3. A projection apparatus, comprising a source of light, a housingtherefor, a condenser secured to the housing an'd adapted to condenselight rays from thesource'of light, a box secured to the condenser andhaving openings through which the condensed beam of light passes, atransparent plate, adjustable supporting means in the box adaptedtosupport the plate in an inclined position in the path of the beam ofparent plate means for supporting the have hereunto subscribed our namesthis plate in front of the slide carrier receptacle 20th day of March,1911.

' in the path of the beam of light, and enbb- N ATHANIEL W. DEXTER.

jective adjustably mounted on the base to WARREN B. MATHER. 5 be movedbetween fixed limits in the path of Witnesses: I

the beam of light. ELWOOD H. BARKELE In witness that we claimtheforegoing we JAMES T. BARKEL W.

